I have to echo what other people have said on here - I don't think it is your shyness that will get in the way but you need to come across as flexible. Looked after children can be challenging (the challenges might not manifest themselves until later) and you need to be able to adapt. What would happen if your child, at a later day, suddenly developed an allergy to cat fur (as happened to my brother at 10 years old)? Would you return the child to social services rather than re-house the cats?
Of course, having animals should not prove problematic (although might do if you live in a small house and the dogs are big) and will definitely be a "plus" for some children who desperately want animals. Risk assessments on each animal will need to be done.
Remember also that taking prospective adopters to panel is time consuming and expensive - and they want to know that you are whole heartedly committed.
The other thing I would say is that after you have been approved as an adopter, you still need to be matched with a child. The animals MIGHT go against you with certain children - in as much as there might be two couples a LA is looking at for a child - one with animals, one without. The child's LA might decide to go with the couple without animals as there is less risk (allergies/attacks/cleanliness etc) so it might restrict you, too, in this way. Would you be prepared to rehouse 2 or 3 of the animals if the right child came up but the child's social worker felt 5 animals would be too much for the child? Please think carefully.
I do think 5 furry animals is a lot and might be overwhelming for a child - but you should have a chat with your social worker and see what he/she thinks. I wouldn't anticipate it being a problem with older children - but might be with v small children.
What I am trying to say is you need to be malleable/appear malleable to social workers who are assessing you.
It is great you are going down the adoption route though - good luck.