Hi Fluty tute
Delighted to hear you're planning to take up the Oboe

. There have been several other threads on the subject of what to buy.
I would warmly recommend getting in touch with Howarth in London (THE Oboe shop) or John Myatt in Hitchin and see what they have available. Student Buffet Oboes are good value these days but a Howarth would be even better. Some people like Ward and Winterbourn others don't. The best thing is to see what your new oboe teacher recommends (we all have our preferences

) and get their help to choose. As you don't yet play yourself, you'll need someone to blow the instrument for you who is an oboist to make sure it's ok.
If finance isn't a problem, get the best you can afford that's still reasonable as a starting instrument. A fully professional oboe probably certainly won't do you any harm now (other than financially!) but it won't enhance your playing greatly initially. Long-term, however, it may pay you to buy something a bit more expensive now and have it last longer. On the whole oboes hold their value, so you won't waste your money if you do so and then decide in the future it's not for you.
Final thought: unless I've confused the names, did I read somewhere else that you're thinking of doing a Diploma on the Flute? Just take care that you don't mess up your flautist's embouchure playing the oboe at a critical stage in your flute playing. It's perfectly possible to play both (and do so well - I've taught people who have done so) but they are very different instruments to blow in lots of ways so take care with your teachers that all is still going well on the flute once you've got an oboe in your hand.
Good Luck with the oboe - I'm sure you'll enjoy it!