For headlining speak to Trafalgar Yacht Services, Hawke House or Roger Nantais in Poole. For sprayhood there are many suppliers but CJ Marine are a good starting point.
For all things Westerly the Owners Association is the most obvious place for information.
Just had a sprayhood made for my Regatta 370 (same as Typhoon). Using my old stainless steel frame the cost was £630 +VAT. Got a few quotes which were all around the same cost.