The costs of running a microlight on a permit or a similarly engined light aircraft on a permit are virtually identical (although depreciation will be higher if it is a newish microlight). I have no idea why Prestwick still does not allow microlights to visit. The Eurostar based there is a light aircraft (with the electric fuel pump!). Shares come up in it from time to time. If you have your heart set on a C42, there are several fields in the area you could possibly base one at that are a lot cheaper than Glasgow! And shares might come up from time to time at Strathaven. However, the hours on all but the one VLA C42 mentioned would not count towards maintaining your SEP.
Why not buy or syndicate a LAA permit light aircraft and your dilemna is solved?