The one you linked is still an HP model (and the cheaper sister to the £120 one - difference is this one only pumps 160l a minute not 400+) You won't need a HP one if you have not got an air floor.
Any of the £10 camping jobs will be fine, just finish off with a stirrup pump.
Or there is this Bravo one:
Electric boat pump inflator Bravo 12V | eBay