Your best bet would be to try the Scottish Register Office.
Scotland has more relaxed marriage laws than their English and Welsh counterparts and as such they will be better placed than ourselves to provide you with advice on obtaining citizenship etc.
Gretna Green (on the Scottish borders) was a popular place for 'elopers' from England in historical times and it is still the most popular place in the UK today for 'eloping' to. You can expect to have a simple ceremony for a few hundred pounds then what you do to elaborate things (reception, transport etc) will be entirely up to you and your budget.
The following websites should help point you in the right direction.
Hope this helps.