I did a similar sort of thing earlier this year to what I think you are on about. I did LGW-MAN-DUB-ORK-LGW with Jet2, Aer Lingus, Ryanair & Easyjet. That was quite good and there was a little bit of time between flights. (http://forum.keypublishing.co.uk/showthread.php?t=53844)
But I’m sure you could do LGW-EDI-MAN-GLA-LGW as well, whiich would be quite exciting & you could check-in online, of course depending on what airlines it was.
Tom