There are three elements to the Warwickshire 11+ - non verbal reasoning, verbal reasoning, and numerical reasoning.
Non-verbal reasoning you could use pretty well any publishers NVR practice materials for - but try to vary it by using material from as many different publishers/sources as possible so you see different formats.
Verbal Reasoning ISN'T what most publishers call verbal reasoning - it's nearer to what most call English. There's multiple choice comprehension, "cloze" tests which involve choosing the correct missing words in a paragraph and/or filling in the missing letters, other vocabulary based questions - practice antonyms, synonyms, homonyns and anything else which will increase vocabulary. Also sometimes questions like jumbled sentences with an extra word where you have to pick out the extra one (along the lines of "the moor plain on mainly falls rain the Spain in"). Maybe crossword style clues with answers with some of the letters supplied - jewelled cup = cha - - - e. Nobody really publishers papers which include all these and nothing else. CGP English comprehension papers/practice book are quite good for that element of it.
Numerical reasoning is another way of saying Maths - but there will be more long problem solving / working out what the sum should be worded questions, and data interpretation for graphs and tables than just being given sums to calculate as per some 11+ practice materials.
Also have a look on the past content
and CEM preperation
threads on the Birmingham section of the forum (Birmingham and Warwickshire exams are both set by the same organisation and have a lot of similarities).