Hi, good to see people starting up BFG. Anyway this is the fleet I use when running straight marines. I like to use the new 2010 update to get access to Thunder hawk anniliators but my armada book list is very similar
75 Master of the fleet, one re-roll
425 Battle Barge
200 Hunters X5
480 strike cruiser X3 with extra shield
320 strike cruiser X2 with extra shield and bays upgraded to bombardment cannons
1500
The armada list is the same except I don't think you can upgrade to bombardment cannons, you only have standard T-hawks and your 75 pt leader has two re-rolls instead of one.
I prefer larger ships to smaller ones but some people prefer escorts. If you like them you can trade out some strike cruisers for some escorts. I think hunters are the best but gladius aren't bad either. Not a fan of the nova as it seems to be a little pricy for what you get. Escorts are harder to use well but can be very useful.
One of the great things about this fleet set up is that you have three classes of ships, large medium and small which are easy to proxy with models from most other game systems. Spartan games makes some nice ships for their Firestorm Armada line that would make some nice proxies. I think Terrans or Dindrinzi would make a fine looking fleet but it is all up to personal preference. You could get a basic starter box which comes with three cruisers, a battleship and six escorts and buy two heavy cruisers to represent the strike cruisers upgraded to have bombardment cannons instead of launch bays. You'd need to buy bases but GW still sell those for 40k.
The other option SM have is to ally with imperial navy. I am not that up on blood angels fluff so I am not sure they are one of the chapters ,like say ultra marines, that would have a large fleet presence and often be combined with IN defending their own domain. If you want to do that route then I'd use the segmentum solar fleet list from the armada book. It will be harder to proxy but there will be a lot more options as you will have two fleets to choose from and the IN has a lot of different ships to choose from.