Two suggestions.
One is look "outside the middle of the country". Most such schools are down the middle of England or in the Edinburgh-Glasgow belt. People don't mind travelling for a CPL course in the way they won't for a PPL course, so why not try relatively distant spots such as (and I've no idea what goes on at these) Lands End, Lydd, Carlisle, Haverfordwest.
Second suggestion, the rules require a licensed OR GOVERNMENT aerodrome. The services have various little used airfields that probably cost them a fortune to run and they might not mind a paying tennant. Mona, Preddannack, West Freugh or Abingdon all could potentially fall into that sort of category.
Alternatively how about Bembridge? - a licensed aerodrome operated by Britten-Norman for flight test purposes, but with little other resident traffic. They might appreciate a lodger, particularly one who might guarantee routine maintenance work and might even be able to do you a deal on twin use.
G