mating season is now, although frogspawn has been seen in very late Feb.
The rest of the year they just seem to wander about, feeding, they do hibernate over winter though.
They will wander looking for food and to explore (no idea why, perhaps boredom)
they sleep during the day and hunt at night, at least they do round here, I used to see more t night than during the day
Your friend is right, as i said they seem to be just passing through when most people see them (unless they have a pond)
There is one option you could consider, that is a frame with a black net on it, but they never look nice and it must be above the water surface otherwise frogs will jump on it, not knowing the net is there, i dont like nets much, but i do have one for a small fountain to catch the autumn leaves.
I think its the south american bull frog that croak a lot, you dont want one of them or the big toad , there are some in thecountry and they eat the uk frogs, some are nearly as big as a small football, and they have fangs and jump up and bite people who dont like frogs
(ok, so i made the fangs and biting bit up, but they are very big)