Hi l have done a bit of mountain climbing in the past, mainly munroes in Scotland.

l climbed Ben Nevis (1,344 metres (4,406 feet) above sea level) and found it quite easy.

Have you got any suggestions as to a slightly harder challenge? Somewhere in Europe maybe?

Im looking for something that would really challenge me but still relatively realistic. Thanks

Go for the BIG WALL! you are ready!

What about Mount Kilimanjaro in Tanzania for a fantastic challenge! See here for info on Kilimanjaro. http://en.wikipedia.org/wiki/Kilimanjaro
A trip of a lifetime l would guess?

Look at the jotunheimen area in Norway, try Goldhoppiggen or Glittertind. It will take you a couple of days to cross the plateau and you should see some wild reindeer up there. The area is also home to the largest icefield in mainland europe.

How about something on the continent? In the Alps.maybe Mont Blanc or the Matterhorn.

You do not mention what time of year u have done ur climbing. If its mainly in summer, try to get out this winter with some instruction from a guide. Climbing Scotland in winter is entirely different to summer. And certain munroes turn from a gentle ramble to a full scale grade 4 winter climb. This will prepare u for a trip to the Alps next year.
As for what to plan, an ascent of Mt.Blanc would be an achievable goal, provided u get some ice axe & crampon experience this winter. Good companies l deal with that offer Mt.Blanc ascents r Jagged Globe & KE adventure. l would ignore a previous comment about the Matterhorn, for a few years anyway, I've climbed it twice & one needs a good many years of alpine experience to climb it safely.
Other than that, there r obviously mountains worldwide but l would not look at anything above 4,500metres or so & more difficult than Alpine grade PD or Scottish Grade 2 or equivalent.
Or a totally different idea is to go on a trek such as to Everest Base Camp or The Annapurna Sanctuary, both in the Himalayas. On both of these u go to over 5000metres & the days can be long & hard. If a 'summit' is not important to u these can be awesome trips & u get to be up close to the world is biggest mountains.