Hello matey,
I'd think from experience it would be normal DOT 4 !! somewhere like Halfords should stock this.
But having said that if you want to do a total fluid change I'd go for Halfords DOT 5.1, Which has a much higher boiling point than DOT 4, I've always used DOT5.1 for the last 10 years or more on all my car's & bikes without problems.
Hope this helps
Cheers CL