I am in the same position, just had my HPE VX MOT'd - it passed with no problems but the tester said I should think about getting the tyres replaced as although legal they are 14 years old.
I have been on
www.blackcircle.com and prices vary for 185/64R14 86H's between £45 to £90 per corner fitted for a renowned branded tyre. Toyo Proxes appear the best value at £51.98 each fully inclusive of fitting and balancing.
Anyone have any preferences as to what an HPE may ride best on. I am not too bothered about ultimate grip, just a good ride quality and longest life- although it only does between 2,000 & 3,000 miles max per year.