In the spirit of lawmaking that feeds heavily on fudge and sweets, the House this week will face a feast of possibilities when it takes up the 1985 farm bill.

The bill is the culmination of an intense struggle between the Reagan administration and the House Agriculture Committee over direction of federal farm policy and spending.

From the basic wheat that makes our bread to the milk, sugar and peanuts that add the zing to the American diet, the bill will regulate the amount and the way that farmers grow those and other commodities.

The administration generally does not like the bill, saying it does not go far enough to reduce federal support spending. The committee does not like the bill either, saying it does not go far enough to stabilize a farm economy undergoing its worse stress since the Great Depression.

And waiting to step into the fray this week is an unusual coalition of Republicans, Democrats, consumer and business groups that has taken aim on key portions of the bill that deal with milk, sugar and peanuts.

Reps. James D. Olin (D-Va.) and Minority Leader Robert H. Michel (R-Ill.) have teamed to support an amendment that would radically change the committee's proposed solution to the expensive dairy surplus problem.

Rep. Stan Lundine (D-N.Y.) will try to repeat a stunning 1981 success, later overturned in conference, by trying to modify the peanut support program.

Reps. Willis D. Gradison Jr. (R-Ohio) and Thomas J. Downey (D-N.Y.) have put together a coalition that will try to alter the sugar support program.

"There's one common denominator runing through all this," Gradison said last week. "These three commodities are the principal ingredients of the candy that is to important to American consumers."

Cheering them on from the sidelines is the administration. Agriculture Secretary John R. Block said last week, "Each of the three has a shot at passing. How we do on those three can tend to be a bellwether for the direction the rest of the farm bill process takes."

He added, "In sugar, peanuts and dairy, the administration is not asking to kill the programs overnight. We say they should be phased down."

The heaviest fighting could occur on Olin's dairy proposal. The influential dairy lobby, multimillion-dollar contributor to congressional campaigns, wrote most of the dairy provisions in the committee bill.

Its answer to reducing the milk, butter and cheese surpluses that have cost Uncle Sam more than $6 billion since 1981 is a "diversion" program that will allow price supports to rise but pay farmers to remove cows from production to reduce surpluses.

Although farmers would underwrite the diversion, Olin and the administration contend that the cost would be passed on to consumers as higher retail prices. The plan also would allow the government to buy herds from farmers who agree to leave the business.

And in a bow to cattlemen who complained that dairy cow culling would send more beef to slaughter and depress prices, the bill requires the government to buy $200 million of red meat each year to cushion the ranchers' expected losses.

Block noted last week that any farm bill containing a milk diversion would run a serious risk of veto. He said President Reagan, reluctantly approving an earlier short-term diversion program, warned Congress not to try it again.

"In the long run, the dairy diversion won't save money," the secretary said. "Consumers will pay up to 60 cents a gallon more for milk. Somebody pays for this. The policy is unsound." The Olin amendment takes a more direct approach. He proposes cutting the present guaranteed federal purchase price of $11.60 per hundredweight by 50 cents in January. Future cuts would occur if farmers do not reduce surplus reduction.

The Roanoke Democrat, who failed twice with his amendment in the Agriculture Committee, said his aim is to return supply-and-demand to approximate balance by cutting farmers' guaranteed prices until it is no longer profitable to produce for sale to the government.

Under the dairy-support program, the government buys all milk, butter and cheese that farmers cannot sell. High support prices, engineered by the dairy lobby, have spurred excess production and created major cost and storage problems.

Gradison and Downey, attacking the committee's sugar proposal, are following a similar tack. They propose to gradually reduce the per-pound support that keeps consumer prices high and requires heavy duties on cheaper imported sugar.

The administration, although it supported the existing program in a controversial deal cut by Reagan in 1981, favors the Gradison-Downey approach.

Block and the Agriculture Department have tried to keep federal costs down by tightening limits on imports, but that has not been entirely successful. The secretary conceded that the department soon will take possession of $138 million worth of domestic sugar forfeited by producers who got support loans through the program.

Lundine is proposing a four-year phaseout of the quota system that regulates the amount of peanuts that farmers may grow. His amendment would direct the government to set support loan rates low enough to avoid acquisition of unsaleable surplus peanuts.

Although he was successful by 91 votes in 1981 with a more-stringent amendment that would have killed the quota system, Lundine lost in a House-Senate conference when House negotiators bowed to Senate insistence that it remain intact.

Lundine and his allies maintain that the current program, with quotas and price supports, has inflated consumer prices and particularly affected low-income families that rely on peanut butter as a major protein source.

Peanut supporters, however, contend that the current program has cost the government little and that a change in the system could cause more economic trouble for farmers who do reasonably well under the quota system.