Hello daxman
Whatever happens as a result of the, how you put it so very politely "shambles" that is brexit, as Bazz suggested it would be best to find out what exactly the BG government intend to do. I would suggest that so long as the UK's comedy of parliament don't start turfing out BG citizens the residency should not be a problem. As far as buying property goes, it may be necessary to set up a BG company and have any properties signed into this company. This is the route I took 7 years ago when I bought my house before BG relaxed the rules IIRC the cost of this then was about 600lv
HTH
Simon