This should save you £8 (£5 if a member). It's worth pointing out that £8 is the Oxford Tube return fare so long as you depart Oxford after 3PM, so you can get from Oxford into London, and get admission to Slimes, for a total of £8.
All you have to do to get on the guestlist is get your name to me (in plenty of time please), and be an Intrusion regular (not necessarily from Oxford), or an OxGoth.
Sophie sexy_sophia or Mark sgt_bookhouse will probably organise an Oxford Tube bunch if enough folk are interested.
You can either e-mail me (email@example.com) or reply here with your name (as LJ usernames are not always obvious) to get on the guest list
(cross-posted to intrusionuk and oxgoths)