Trust your gut instinct!
Nurseries buff up when they have a 'show round' so you will only see the best in all rooms. Go back for a second visit outside of typical show round times (varies by nursery, but avoid lunch time usually 11:30 / 12pm) you will then get a real feel for what's going on.
Ask about the ratio for two year olds because any nursery who is following the new ratio of 1:5- though perfectly legal is not thinking IMO of the children's or staff wellbeing. Meeting the developmental, educational and care needs of two year olds on a 1:4 ratio is hard enough for the toddler staff the new ratios are absurd!
Visit the pre-school room for 3-5 year old children and ask about the learning and development requirements within The EYFS and to see an example of planning. It should planned purposeful play with a mix of child led and adult led activities that helps every child make progress. Ask how they observe and track also.
Do the children look happy and engaged? You should see some children's mess from activities , such as sensory play painting and messy play, but the environment should be both clean, tidy and calm. It should not be chaotic.
Staff are they happy and engaged with the children.? Many nurseries have high staff turnover. What is the composition of staff in terms of experience and qualifications? Be cautious of any nursery that has too many apprentices or inexperienced (usually younger staff).
Their key person system - your child will have a named key person who looks after their interests and in 0-2s should dip all of their personal care, where possible. Any good nursery should have a secondary/buddy/back up key person system in place . The buddy key person will support your chid if their main key person isn't in where possible. It is not always possible due to shifts starting and ending, holiday and sickness.
Every staff member should be paediatric first aid trained. The legal requirement is one member of staff, but walk away from the nursery if not every member of staff is not first aid trained. Some nurseries have their staff trained in Millie's Mark, which is additional first aid/choking training.
The Baby room leader will have a level 3 minimum and needs to have had specific training and experience with 0-2s
Level 2 staff work under supervision , Level 3 or above staff are the ones in supervisory positions- alt least one member of staff in each room must be level 3 qualified.
Ask what they would do in the event of being over ratio? This will tell you all you need to know. The ratios at the moment are 1:3 0-2's, 1:5 2 -3's (1:4 is better) and 1:8 in pre school, but in pre school this can change to 1:13 at certain times of the day if a level 6 (degree level) member of staff is a qualified early years teacher with early years teacher status or qualified teacher status.
Trips- it is a legal requirement that children have access to outdoor space. If the outdoor space is limited or none then it is expected that nurseries take the older children out daily in all winds and weathers.
Nursery trips form an important fun part of the nursery day and extend the children's learning. They are all risk assessed and it is usual for the ratio to decrease on trips ( e,g 3 year olds on a trip will drop to a 1:4 ratio rather than 1:8 or they should) it would never just be one person. Babies are safest on trips as they are usually in (triple) buggies.
your choice, but if you are that parent and do not let your child go on a trip - the nursery staff will probably dislike you because you may stop them taking other children in the room on a trip because the ratio will be messed up.
Food - ask to see an example of the food if you can. I was once in one nursery where sausage casserole was on the menu- what was served up was hot dog sausages from a tin, tinned tomatoes and tinned veg.
Finally try and relax I am sure your LO will enjoy nursery once settled.