There are sheep dog trials all over Great Britain, every weekend of the year. Wherever you go, a car is necessary, although you can incorporate some travel by train. A good local map is essential; a large-scale Ordnance Survey map, available at local newspaper shops or bookstores, marks farmhouses, ancient ruins and public walks through private fields.

A day's admission to the trials generally runs from $1.50 to $3, parking about $2.50 extra. The only seats may be a few straw bales, but you can often park at the edge of the course and watch from your car, or take your own chairs or blankets. For more information: International Sheep Dog Society, Chesham House, 47 Bromham Rd., Bedford MK40 2AA, England, phone (0234) 52672.

Among the competitions scheduled for late summer and fall:

Lake District Sheep Dog Trials, today and tomorrow in (respectively) Kendal and Muncaster.

Longshaw Sheep Dog Trials, Thursday through Saturday, Longshaw Estate, Grindleford.

International Sheep Dog Trials, Sept. 10-12, Woburn Abbey Park, Woburn.

BBC International Sheep Dog Trials, Sept. 15-20, near Derwent Water. For details: Ian Smith, producer, "One Man and His Dog," BBC-TV, Kensington House, Richmond Way, Shepherd's Bush, London W12, phone (01) 743-1272. WHERE TO STAY: Hotels in all price ranges are available throughout these areas, but to delve deeper into country life, consider a farmhouse bed-and-breakfast. Comfortable, traditional, friendly and reasonable, they have rates ranging from about $15 for one person to about $45 for two. An example of what's available in each area:

Heart of England, Woburn area: Will Farm, Gayhurst, Newport Pagnell, Bucks. SZ MK16 8LT, England, phone (0908) 611489. A 505-acre mixed farm with a 400-year-old stone-built farmhouse in a small hamlet on the River Ouse.

Peak District, Longshaw area: Nether Padley Farm, Nether Padley, Grindleford, Sheffield, S. Yorks. S30 1HP, England, phone (0433) 30073. A 20-acre sheep and beef farm with a Georgian farmhouse furnished with antiques.

Lake District: High Fold Farm, Green Quarter, Kentmere, Staveley, Kendal, Cumbria LA8 9JP, England, phone (0539) 821531. A 500-acre mixed farm with a 17th-century farmhouse and panoramic views, set in a village in a secluded valley.. WHERE TO EAT: Lunch at country pubs is hearty and inexpensive, with bread and cheese or pa~te' for around $3, or more substantial steak-and-kidney pie for around $5. Remember pub hours: from about 11 a.m. to 3 p.m., and 6 to 11 p.m. Many pubs also serve evening meals; some are also hotels. A few suggestions:

Heart of England, Woburn area: Black Horse, Woburn -- a wood-paneled, friendly old pub; Rose & Crown, Ridgmont -- an old brick house with a low-ceilinged bar, wood settles, dogs before the open fire; Swan, Astwood -- a partly thatched, early 17th-century pub with antique seats and tables, low beams, inglenook fireplace and bedrooms from about $45.

Peak District, Longshaw area: Checquers, Froggat Edge, on the B6954 -- a 400-year-old white house (an inn since the 18th century), with high-backed, winged settles and well-waxed floorboards; Old Bulls Head, Little Hucklow, off B6049 -- a meticulously kept traditional village pub with oak beams, built-in settles, antique household tools and a coal fire.

Lake District: Masons Arms, Strawberry Bank, Cartmel Fell, a few miles south of Windermere between A592 and A5074 -- a remote white house with a friendly atmosphere, polished flagstones, low black beams, big log fire and Jacobean paneling; Pheasant, Bassenthwaite Lake, off A66 -- a gracious, old-fashioned inn with a cozy bar, rush seats, cushioned settles, big log fire, chintz sitting rooms and bedrooms from about $40. INFORMATION: The British Tourist Authority, 40 W. 57th St., New York, N.Y. 10019, (212) 581-4700, has free guides to all the regions of Great Britain. It also lists all local British Tourist Information Centres, the best sources for brochures, bed-and-breakfast listings and maps. Tourist information centers will advise on car rentals and some will even book rooms for you.