Trim Stab - filing a flight plan doesn't automatically give you the right to continuous climb up to your filed cruising level. If there is traffic in the way, which there almost always will be at some point, then you may have to level off lower temporarily. CAP493 states any aircraft already at your requested cruise level will get priority over you - that's the rules we work to. In the UK we will do our best to get you to your requested level as soon as possible. The only reason you wouldn't get it is if someone else who is on the same route is there already at that level, or if you've filed to avoid flow restrictions on certain sectors (but even then we'll often let you climb into the sector on an ad hoc basis when we can see what the traffic situation is like and make an informed decision based on that). I know certain other countries in Europe use blanket level caps for specific destinations, but I can only speak for the UK. There will however often be procedures requiring us to present traffic in such a manner to those other countries, preventing us from giving you your filed level. I hope that answers your question.