If you just like to get out there and run rather than take part in organised races then you might like to try some of the challenges featured on www.gofar.org.uk a website that aims to provide a single source of information on ultra-distance challenges from around the UK. Although all the routes are in the Lake District, the Peak district, the Pennines, Wales or Scotland.
Just to give you a flavour of what is on the website here is an extract from the description of the Brecon Beacons Traverse.
'Also known as the South Wales Traverse, this 24-hour challenge involves 72 miles and some 17000 feet of ascent. It traverses 31 summits in the Carmathen Fan, Fforest Fawr, Brecon Beacons and Black Mountains areas and may be completed in either direction.'
There are some absolute gems in amongst all the routes and if you so desire you could aspire to become a member of the Over the Hill Club.
'Full membership of this prestigious club (!) is free but is restricted to over 50's. Under 50's may complete the route and will be recognised as Associates of the club on the understanding they repeat the route when senile enough! Membership is achieved by completion of the Over the Hill route: a roller-coaster circuit linking together seven summit pillars in the Howgills and Great Shunner Fell areas. All completions must be registered using the registration form which can be printed from the Over the Hill route page.'
After that you may like to reward yourself with the Canary Islands 3 Peaks Challenge.