Ceri,
Buy a small tent now, a one man/woman one, and later if you want somethng for two people go for a three man that will probably only weight .5kg more than it's 2man equivelent. The 3 man tent will be so much more comfortable for two than say a two man is for one. 
That said I have carried my 6.5kg 3 man F10 Spindrift on a few solo trips up mountains but I can't recomend this unless you need to carry excess weight for training purposes etc or are just plain crazy.
One last thing about an akto (and other hillebergs)is speed of pitching. Put a couple of pegs in one end, put in pole, put in rest of pegs and guylines. The TN will take considerably longer to pitch.