we have suspended wooden floors whats best and most cost effective conventional central heating or underfloor heating

Underfloor heating systems are available for suspended wooden floors but the cost involved in fitting it would be a lot higher. literally every floorboard in your bungalow would need taking up and you would need to insulate between joists to meet requirements of part L and that's before laying a single pipe. That said it does mostly get rid of unsightly radiators (you may need a down sized one here or there for the coldest of nights) or gas fire installations alongside underfloor is an option. Good luck George Ray

conventional is the most cost effective i hope this helps

Conventional is the most cost effective and controllable. Under floor is a luxury and normally requires conventional radiators as well for really cold spells.