I don't think the OP is posting so much about her husband being OK - she knows how to get an ambulance to get him to A & E, and they will deal with the problem then - but about coping with the logistics of life in the caravan without him, and about visiting the hospital without driving.
Make friends with the organisers of the site as soon as you get there, and mention your worries. They are very helpful if needed, so are fellow caravanners.
Is it a touring van or a static one? If it is a static, daily life will be the same as in a house. It will be wired and plumbed in, with the same facilities as home.
A touring van will need you doing things that your OH probably did (as mine did) - filling the water tank and emptying a Portaloo for instance. You presumably have a rolling water-barrel, and the Portaloo tank can be strapped to a sack barrow to transport it to an emptying point. If you have not done these things, get him to give you a demonstration in case it is necessary.
Same with managing gas bottles if that is how you cook and heat the van (but these days touring vans have microwaves, electric cookers and heaters. When we started decades ago, we had gas lighting with fragile gas mantles that disintegrated if they were shaken around while travelling, a one-burner gas ring and a grill that took one slice of toast at a time and left that pale round the edges. I remember trying to grill sausages after sunset one evening. If I turned up the gas on the grill, the lights went out. If I turned it back down to see, the sausages stopped cooking. We travelled with a box of new gas mantles, and mostly ate tinned stuff or ate out.)
Go - you will be OK.
