Agree with everything stated here. Amount of funding for the vouchers depends on the county you are in - each sets slightly different amounts per session.
Many playgroups and nurseries take vouchers now but please be aware that the vouchers do not necessarily cover the entire cost of the session. Our local playgroup is "free" from the term starting after their 3rd birthday as the cost is totally covered by the vouchers. However, the nursery I choose is not. We can still use the vouchers but pay a lot on top to cover the extra costs.
You do not need to worry about doing anything to collect these "vouchers". Once you have applied and start at a playgroup/nursery that takes vouchers, you just fill in a form they will hand to you and the playgroup applies for the funding from the council on your behalf. When I started I thought that the vouchers were a physical thing that you got in the post and handed over per session! The term "coucher" is a little misleading and there is nothing really for you to apply for. This saves you having to find the cash and then be reimbursed. All you will need to do is give date of birth, address and show the group a copy of the child?s birth certificate to prove their age.
One of the big things to consider between various playgroups and nurseries apart from cost, is how they are run. Many are run by employed staff and have a committee of parents overseeing their employment, policy and funding. Others are run by staff with similar set up but ask parents to do "duties" on a rota basis. This has obvious advantages and disadvantages depending on your personal circumstances and feelings about other parents being involved in the "hands on" aspect of the session. In some of the smaller groups that rely on parents to boost the adult to child ratio to keep costs down, you can find yourself being asked to do a duty (give up your morning) even as much as once a week. This may appeal and seem like a great thing to do or not - depends on how you feel, how much time you have and also how your child responds to having you around. I was happy to be around and help out but my child hated it - became clingy in the sessions I was there and it was a disaster. My other child loved having me around and it was great.
Another aspect to consider is their play policies. Some groups are very "outdoorsy" and will take the children on lots of walks regardless of the weather etc and other groups will have a very different attitude, choosing to stay inside all morning as it "might" rain later.. Every group is different and have different approaches. Go visit and ask to stay for a taster session with your child to find out. The only way you will know what appeals to you and your child and what is out there is if you do a little research and ask around.
Good Luck. The difference between groups can be HUGE. It can also play a major role in the happiness and development (or not) of your child so take your time deciding.