Yes, you should use the Nelson standard format papers, but you will need more papers for extra practice. For VR, please read Patricia's posts in the Buckinghanshire and Verbal Reasoning sections. She really is the expert!
If you have more questions, post them in one of these sections because Patricia doesn't always read posts in regions other than Bucks.
As for Non Verbal Reasoning, here's a quote of one of my previous posts in 'Kendrick School, Berks' in case you haven't seen it. As I mentioned, all the papers in Slough are Multichoice, and I do not know the details of the standard format.
When I refer to the NFER pack, I mean the Nelson NFER papers that Bewildered mentioned.
My son took the test for Slough last year. They include NVR in NFER multichoice format.
I didn't have time to do a lot more than the NFER pack, but here's my thoughts about the other papers I got.
The Bond "How to do verbal Reasoning" and The Learning Togeteher Practice Papers have more question types than the NFER that only have about 7 types. I didn't use them a lot and not sure how good they are. They are easier than the NFER papers, and may be good to start with. Just before the exam, I downloaded some E-papers from this site. The '11+ Exam' papers are close to the NFER types in term of content and level (may be a bit harder). I thought that the MW were too different.
Sorry if the info is a bit thin!
A quick tip: Doing a small amount of NVR (10mns) regularly (more or less daily) worked well for my son.
Overall I found that NVR does not have as many quetion types as VR, and does not require as much practice time. Just an opinion. Someone else may disagree..
Also, you may be able to receive some help from the people who run this site.
Please don't hesitate to ask if you have any more question.