I would have thought that they would be glad to see you. Don't forget that at this time of year the Reds are doing three practises a day but they are only for twenty minutes or so. Can't remember what the MOD rate is but £38-40 rings a bell. I've flown from Scampton and they are a friendly bunch.
If you can't get in at Scampton then Wickenby would be your best bet as Sturgate is shut during the week, although you can still land there if you call Eastern Air. In fact I would go for Wickenby anyway as scampton is easier to get to. I don't know what you are flying but check out Wickenby's runway length as it's not that much. Easy enough to get spamcans in and out of.
By the way the mob like oval circuits so the snappier your arrival the better. No bomber circuits.