Well, first you may want to find out if BA counts LGW and LHR as the same city?? Persumably, yes, but airlines are airlines!!

BA has some connections at MAN.

There's always EI in DUB too.

Plus you may be able to book yourself onto AA code-shares on SR and SN thus opening up connections in BRU, ZRH and GNV.

Just some thoughts ...