Hi,
I will be commuting from Ilford to West Byfleet every weekday morning at about 7am, returning about 17:30hrs.
I am 54 years old.
I have an oyster card.
I presume the cheapest route is to go from Ilford to Waterloo on the underground (Elizabeth line and Northern line)
...Then to go on South Western Railways from Waterloo to West Byfleet.
I can use my oyster to get to Waterloo.
Then is there a railcard i can get to get cheaper fayre from Waterloo to West Byfleet? (return)
The only Railcards that you would eligible for, unless you have a qualifying disability (the threshold may not be as high as you think), are a veteran or are travelling together with someone else, would be a Network Railcard or an Annual Gold Card.
The latter is a "freebie" you get for buying an annual season ticket to/from/within the Golf Card area (i.e. the southeast plus a bit more) - the cheapest qualifying season is Hatton to Lapworth for £184 a year.
Neither a Network Railcard nor Annual Gold Card would be of use on the outward journey, as there is a time restriction meaning they cannot be used to discount tickets before 10am and 09:30am on weekdays, respectively. Network Railcard discounted fares additionally have a minimum fare of £13 on weekdays.
In terms of season tickets, your cheapest option would likely be to buy a West Byfleet to London Zones 1-6 Travelcard - this would cost £104.90 a week. There is a slight discount for buying a monthly season (£402.90) and a bigger one for buying a yearly season (£4196).
Being a Travelcard, this would be valid on all National Rail (including London Overground/Elizabeth Line, but excluding the Heathrow Express and Southeastern High Speed services) Underground, DLR, tram and bus services within Zones 1-6. So it would give you total flexibility on your route and avoid you having to pay extra for any journeys into London on the weekend/evening.
I have seen that there's a slightly cheaper, if slightly impractical option. This would involve using Oyster from Ilford to Surbiton - avoiding Zone 1 via Canada Water (touching the pink reader there, or at Whitechapel). You would use a season ticket from Surbiton to West Byfleet. You would have an Annual Gold Card applied to your Oyster so as to provide a discount on the return journey.
This would add up to £83.10 a week, plus £184 a year for the Annual Gold Card. This isn't a huge saving, and it's poor value for money when you consider the much longer journey time - and requirement to step back a train at Surbiton in each direction in order to exit and re-enter the barriers to touch in/out your Oyster.