There are plenty of seminars held in the UK. The BAB web site lists a few of them, see here
Others are spread by word of mouth, for instance Endo Sensei was in Ireland for a weekend 2 weeks ago. Chiba Sensei is coming over to the British Aikikai summer camp this summer, further details here
I don't know where you train in Manchester, but my dojo is a member of the Lancashire Aikikai, we have a number of dojo's in and around Manchester, if you belong to one of them, they usually keep up to date on seminars going on.