ADVICE re NATIONAL ARCHIVES

[HOWMUCH]

Hello
I am generally on The Lancashire board but I have since traced a possible ancestor that was an excise officer at the time of his marriage at Manchester in 1795 . I have been on the National Archives Website and there may be a chance that his appointment , postings etc are recorded .
Before I try to make arrangements to research this via their staff , I was wondering if any person was attending the centre for any reason and would be kind enough to have a look for me . I have never been to the centre and therefore I do not know the set up . If it is a too involved request then I would understand .
Many thanks
Eric