This is the one i've used, others are probably finetoo though
Sorry for long link, mobile eh.
Rat guy here.
There are three options here.
He is passing through your area which is between his nest and food source.
Rats nest where it’s warm, quiet, sheltered, and near food. Go around your house and look for any gaps you can get a finger through. Look for gaps in brickwork, broken drains, gaps where pipes enter/exit the house, and block the up with rapid set mortar. Cats are good because they are active at the same time as rats (2am - 5am) and are a threat to the peace and quiet a rat loves. Rats are agoraphobic which is why they run along walls and hide under cover, so pick up any crap that’s lying on the ground.
Rats have a super high metabolic rate, and instinctively know what foods are high calorie. They go after nuts, pet food etc, but they also look for a reliable food source, Like bird tables. They will hop through a cat flap to get to the cat food.
Seeing a rat during the day indicates that he currently doesn’t have a nest with readily available nighttime food. He is likely out during the day because he needs to eat and is looking for a reliable food source. He may also have the added pressure of a nest with kids that need food.
So to get an idea of what’s going on, I would advice getting one (or more) of these cameras. They last 3 months on a set of batteries, and click anything that moves. You’ll see rats if they are moving near your house. It’s a great way to see where they are going, what food they are carrying, how many etc. it’s also a useful security feature if you hide it well enough.
Good luck.
I bought mine from a local garden centre, but it looks very similar to what's on the link below. As soon as the temperature starts to drop I put my tree inside the cover and leave it under there until around this time of year. Don't forget to water it every once in a while as the cover is water resistant.
It's tough cos they're all almost identical Chinese imports and I don't know how much I trust their safety. However I got this one from Amazon and it seems to keep stuff at around 25c (I cover the seeds with a mushroom container to keep the moisture in). Had it a week or two and not burned anything down yet, but I wouldn't keep it plugged in at night or when you're out just in case
RINBO Seedling Heat Mat, Heating... https://www.amazon.co.uk/dp/B07GJF8KLV?ref=ppx_pop_mob_ap_share
Type in your postcode and see if offer is available to you
They do smaller ones too, these 330L ones are £8 each or £12 for two
They're subsidised by councils, this is the exact bins for £30 each +£7 delivery on Amazon