Much depends on the make of your tent. If it is decent quality it will stand up to rain and wind - if not, it is posible that strong wins will drive rain through the outer membrane.
be warned, any wind at all when you're trying to pitch the tent will lead to swearing and arguments. make a plan - make sure all your helpers understand their roles - work from the windward side, pegging this down first before trying to raise the poles.
You should invest in some sturdy plastic pegs. The pegs should go in at an angle so they don't just lift out.
A sheet of builders polythene spread out on the ground before you pitch helps preserve the (inevitably flimsy) integral groundsheet from damage. Just peg straight through the poly - check it in the bin when you leave. Flattened layers of cardboard boxes laid at the tent entrance help to absorb mud and keep the interior drier/ cleaner. Above all, remember never to camp in Britain because it is cold, wet and muddy.