your picture shows two useful things:
A much larger steel staple provided with the lock. The better Yale locks (to the British standard) that you find in the DIY sheds or at locksmiths have this , instead of the little metal staple provided with traditional nightlatches, which appears to me to be designed to pop off without much difficulty.
The big Yale used to be called a Titan, I will see if I can find a pic
Your picture also shows a reinforcing strip. these are also available under the Kickstop of Lockguard brands. the problem here is that it only starts to give reinforcement after the lock's staple has started to give way.
A mortice latch is generally preferred as it is stronger. In my own house I use a Chubb 3R35 which would probably cost you £100 or more fitted (you will see one on the front door of almost every high-street bank) but it does not meet the British standard and ought to be used in conjunction with a deadlock (if you have plenty of money you can get a matching one operated by the same key, but you can guess this will be expensive).
I'm not a locksmith so don't know what else to recommend, but there should be someone else along more in touch with the market. there is probably a Eurolock thing though I'm not very keen on them myself.
Banham, Ingersoll and Chubb make some very good locks. not cheap though.
A big staple like this, secured with long screws to a sound frame, will be much more resistant to being forced open.