You will want a well-fitting BBQ Cover - no point buying an expensive Gas BBQ and having it rot in the sunlight and rain! Given the windy UK, also make sure it can be tied on...we have had so many blows! BBQ cooking tools wise - you want BBQ tongs (avoid the burnt fingers), Spatulas (yes, more than one as I always lose them) and a fork to rescue stuff that falls under the grill.   Sure, if you want to look at the BBQ Daddy (or mummy!), then an apron too, but ditch the BBQ chef hat as that's too dorky!