Biking and hiking/walking self-guided tours in Wales?

We have used Contours Walking Holidays and were happy with their services and selection of overnight accommodations. However, we have not walked in Wales.
https://www.contours.co.uk/wales

Looks like Contours has a number of short walks, some being segments of classic walks like a section the Offa's Dyke to circular walks. Some of Contours walks have the option of walking the same route in more days making a "moderate" walk and "easy" walk. Contours also offers the flexability of adding rest days.

This link describes what is included in a Contours walking package:
https://www.contours.co.uk/what-can-i-expect

Consider part of your time in Pembrokeshire = SW Wales. To reach this area - take the train from London/Heathrow Tenby (ideal for south Pembrokeshire)*. (It is a long trip so I would advise that you break the journey in Cardiff for at least 1 night). Trains = www.nationalrail.co.uk (For long journeys - pre-book advance tickets on specific trains around 11 weeks in advance for the lowest prices). Tenby > http://www.tenbyvisitorguide.co.uk
* For north Pembrokeshire - take train to Haverfordwest or Fishguard.

Check out these:> https://www.celtictrailswalkingholidays.co.uk/walking-holidays/pembrokeshire-coast-path/
http://www.visitpembrokeshire.com/explore-pembrokeshire/coast-path/
https://www.contours.co.uk/pembrokeshire-coast-path-trail
Of course, you could simply choose a convenient place as a base and then use the local buses to go somewhere and walk back to your base. https://www.pembrokeshire.gov.uk/bus-routes-and-timetables/bus-routes-list-coastal-buses

You may then like to relocate to Snowdonia (NW Wales) - although plenty of other areas also have hiking such as the Brecon Beacons. To get from Pembrokeshire to NW Wales, you will need to use buses - although from Aberystwyth/Machynllleth northward there is also a railway* going up the coast. For buses in Wales:> https://www.traveline.cymru
Also check http://www.trawscymru.info/routes/ - which are free on weekends.
*https://www.scenicrailbritain.com/lines/cambrian-lines

https://www.nationaltrust.org.uk/lists/top-10-walks-in-snowdonia
https://www.forestholidays.co.uk/beddgelert-snowdonia/walking-and-hiking/

The things I have mentioned so far are hiking/walking. (You can’t cycle the Pembrokeshire coast path because it is to rugged - as are many of the trails in Snowdonia). For cycling >https://www.visitwales.com/things-to-do/activities/biking
Cycle route in southern Snowdonia > http://www.mawddachestuary.co.uk/cycling/mawddach-big-8.html

For flying home from NW Wales, Manchester is the nearest airport. (You could fly in to Manchester if doing things in reverse. If so, I suggest a first night in Chester).

We visited South Wales in October 2017 and loved it. Very scenic and the people are very friendly. Lots of castles and history.
We are cyclists and have done long distance cycling (500 miles in a week). The terrain in Wales is very hilly, so chose you ride well.
Don't miss Tenby and St. David's. Lots of see around the Cardiff area.

Thanks for the replies, folks. I'll keep looking for cycling tours, as that's the prioirty, but I now have some nice suggestions for walking tours.

The following map will show you recommended cycling routes that usually use backroads with less traffic or former railway lines etc.https://www.sustrans.org.uk/ncn/map