Yes, I had the same problem winter before last. Wickes do a roof repair product that you paint on (very thickly). It contains some sort of fibre that bridges the split. I had a very large tear (2") where the wood underneath had expanded with the wet, I covered these wide gaps with stick on flash banding first then painted the sealer over, but I'm sure the sealer would be fine on it's own for up to 1/2" or so.
http://www.wickes.co.uk/high-performance-acrylic-waterproofer/invt/240148/
http://www.wickes.co.uk/hi-tack-flashing-strip/invt/243006/