In answer to the original question, no it is not hard to get through Oxford's aptitude test............if you have the aptitude for it!
The whole point of Aptitude tests in this case is to find out if you are suited to:
a. The rigours of an Integrated course
b. The line of work you will ultimately go into
Trust me, given the serious financial committment involved you owe it to yourself to find out if you are what the industry is looking for. I mean, what is the point in getting through a half arsed assessment and paying £100k only to realise you weren't the right kind of person for the job at the end. That could have bought you a tidy flat ;-)
No but seriously you see where I'm going with that, and I wish you the best of luck getting in to OAT.
When you get to the psycho profile, just remember that you should not, under any circumstances, get diverted from the general questions into thinking of specific examples. To illustrate my point, a question commonly asked in these sorts of things is:
Do you get frustrated when stuck in traffic?
A seemingly innocuous question, but you'd be surprised how many people immediately think of a time recently when they were trying to get somewhere urgently and got held up in traffic and you will reply YES (if answering instinctively as per the brief.) The questionairre is a generalisation, so don't ever ever ever ever start thinking of examples. Say to yourself when faced with that question: On a regular, normal day, would I be overly frustrated by a minor traffic hold up?
Most people will then calmly and TRUTHFULLY answer no, and if you follow this way of approaching these questionaires then you will too. (That is unless you are a psycho baby boiler who has no business going into the aviation industry anyhow!) It's all about filtering out the unstable ones. Pilots are supposed to fit into a nice neat pigeonhole labelled 'stable extrovert' - something you will learn about in Human Performance. Make sure you are the stable extrovert they want you to be before you go into the industry, I think there are many more of these questionnaires to be filled out in the ensuing years!
With regard to the Sim check, its a piece of cake unless you are afflicted with the claw of Jeremy Beadle and have his interpersonal skills. They want to know if you can digest basic instructions, can multi task, and can GET ON WITH THE GUY SITTING NEXT TO YOU! Don't be afraid to concentrate on completing the manoevre before you tell them the square root of 63!
Oh and if you get through, enjoy the 'team building day'. You will never say the word 'tripod' again without it triggering memories of OAT's car park and dodgy lunch!
All the best.
The Camel