Your office will be at Suntec, so you might want to focus on condos
along the new circle line if you want less than 20mins commute time.
There are a few stations that are near Suntec including Esplanade & Promenade on the circle line, so you can get off conveniently, depending on which building you are working within Suntec. Of course, you can also get off Cityhall but its a good 10-15mins walk to Suntec, depending (again) on which building you are working in Suntec. Assuming you are coming from UK (since you mentioned your gf's employer in UK), you might need some getting used to, with Singapore weather.
With a budget of $3k, don't expect to find a brand new 2-bedroom property
. You will probably need to check out the older apartments/condos. You can investigate if there are any suitable condo
s within your budget around Stadium/Mountbatten train station. Its a popular expat area and there is some seaview, or sort, depending on which condos you are looking at.
If you are looking at Dover/Clementi/Buona Vista, note that you won't be able to get to office via train within 20mins (including the short trek from Cityhall to Suntec).
Clementi is more heartland area (i.e. more locals). Buona Vista is near Holland Village, which is another popular expat area. There are several buses that goes from Holland Village to Suntec and I understand the bus-ride is about 20mins.