Short answer: You should absolutely go for Silver.
Long answer:
World Traveller Plus
WTP is typically double the WT fare. However with WT fares being, say GBP 400-600 normally this is not necessarily a huge amount extra to pay.
Unlike First at GBP 6k and CW at GBP 3k!
The WTP seats are quite a bit more roomy than WT and I always think that it is worth paying for the more space if you can.
Paying for WTP to earn status
Four longhaul returns in WTP will earn you Silver and a further ten will earn you Gold. So if your expected travel plans materialise you might find yourself a Gold in just over a year from now.
I absolutely think that it is worthwhile to earn at least Silver by flying WTP because access to the lounges, business class check in, the ability to select your seat in advance, additional baggage allowance and potentially more accommodating handling in the case of disruptions together could be worth a lot if you are not already travelling in CW or First.
A friendly word of encouragement
I would say that you should choose your frequent flyer program quite carefully now, not necessarily for the mileage or status that you will acquire immediately but for that which you might attain in the future.
You are only 23 and when I was 23 I did not dream of funding my own longhaul business class travel four or five times a year. However now I am 29 I find that I have the disposable income to spend on longhaul premium air travel.
I hope that in a few years time you will also be able to fly longhaul in business class. You should have the experience by then to persuade your employer to permit this for business trips, or to change employer if they do not play ball. You should also be earning more, enough to fund a holiday in Club World every year.
The BA scheme is a good one to focus on because you can take advantage of the miles for upgrade facility to travel in Club World at a fare of GBP 600 - GBP 1k. The Club World seat is also excellent, making BA a good carrier to be with.
I hope that what I have written helps.