Assuming (from the exact grid reference) that you're approaching north west and departing north east I think I'd be looking to be pulling well into lane 1, and signalling my intention to move across into lane 2 at or around the solid white line across the road, and to be central in that lane by the writing on the road...
But traffic conditions obviously determine this alot. My current "hassle" roundabout is
Google Maps. I travel West in the morning and East in the evening.
East is OK - the left lane filters so I stick on the white lines between lanes 1 & 2, then follow round the roundabout to the exit - the morning is "interesting", I tend to take the middle lane if it is available, but generally end up doing the same, and just get out onto the roundabout quicker than the cars do - then they're behind me and at least aware of my existence as I follow the white line round and merge at the exit.
Never had an issue doing this, although as I have a fairly good view down the A46 when I approach the roundabout I have been known to fly through - 20+mph straight onto the roundabout past stationary cars at the junction - the time when a work colleague (who'd left work 25 minutes earlier (and 400 metres away)) saw that he did say the next day that it looked quite "brave".
As has been said you aren't holding the traffic up, *you are the traffic* - and this looks fairly urban - I can only assume it's a 30 or 40 limit, so you're really not going to be impeding people much - not relative to the traffic lights at any rate...