Whilst Didcot is a bit average, there are some unexpectedly pleasant villages nearby. I'd suggest something like Didcot - East Hagbourne - Astons - Moretons and loop north back to Didcot. If you turn left from the station there is a decent cycle path, this continues to Hagbourne if you cross at the roundabout. There is also a cycle route back into Didcot from the north, I've never tried this one but am told it can be muddy.
For a pub stop there is a community owned pub at South Moreton, no experience of it but if it's community owned it shouldn't be bad.
But take the advice elsewhere and do a recce.
