First, I would check warranty coverage and then the cost on a replacement.
Second, I would get several quotes from qualified service repair centers then compare the two to see if it's worth having fixed...
Sorry, I don't know of any UK repair centers.
If it's not under warranty, you could take a look at it yourself but understand that you might make things worse instead of fixing the problem which can increase repair costs.
In my experiences, I've found a smoking power supply is often caused by rectifier diodes in the power supply section going out. More often than not it is identifiable by burn marks or smell. There's a good chance that this blew the fuses as well. Open it up carefully with the unit off and unplugged and take a close visual inspection inside. You can used canned air to blow out any dust. Dust is made up of all kinds of things and sometimes it's conductive causing a short so clean it up carefully and once you start be sure you get as much as possible out or you may just move the potentially conductive dust/material to another area causing more problems.
It could be many things but I find, as an electronic instrument repair technician for Kurweil Music Systems that these are common problems.