Holloway - I understand why you are tempted, but don't get yourself a GPS while you are doing PPL navexs. You are going to have to do the skills test without it, so better to learn good old chart, compass and mark one eyeball navigation now.
If you are 'uncertain of position' then use VOR/DME etc. to position fix - that's OK, and taught as part of the PPL. Waypoint following using a GPS isn't.