turn up your wall stat
boiler should kick in
when boiler running check the pump to see if it's running.
which will probably be located in your cupboard with your copper cylinder.
also check the diverter valve above the pump it should have a lever on the end push that across afew times may be sticking.
sounds like you may have a sticking pump because of not being used.
hi-spec plumbing, September 2007