I made 78 donations before ill health stopped, most of them at the time you just turned up and waited and I quite looked forward to seeing the my twice a year friends. In regards to eating etc I always carried on as normal and afterwards it was straight to the pub to replenish my fluid level fluid
Well ummmm, I dont know what the recomendation is now a days but for years the nearest centre was in the next village about 5 miles away and I never had any trouble driving, so long as you have your cuppa, biscuits and a few minutes sit down you should be alright