Apologies if this is old ground...I really need some advice. Bear with me!

I currently live and work in the UK (self-employed), and I have a girlfriend in Spain. My situation now is that I am having to sell my house as I cant afford the mortgage, but I still need a base here to continue working part-time. The rest of the time I will spend in Spain. I also need somewhere as a base to visit my kids, and a retreat for girlfriend and me. The most practical option, and the most attractive in many ways, is to buy a static caravan on a holiday site. Its within my tight budget and the site owner thinks we can work things out between us re. time I spend on the site, etc. A problem I foresee is that I will have no residential address here, as at the site I would be c/o. Is this going to be a problem for everyday things like bank accounts, etc? In fact anything that requires an address?
Anything else I should consider? Sorry if this is long-winded and vague. This has all come to head in the last few days...
Thanks... Norman