Sybil I signed up for 'Which' last week so I looked up the best pushchairs for you and the smallest/lightest one on a budget is the McLaren Quest Sport which came 5th overall. It's suitable from birth and it costs £100. Which is good as totally independent and they thoroughly test everything. Here is the review:
Good for around town, the Best Buy Maclaren Quest Sport is a basic lightweight four wheel stroller.
It is easy to push and steer, but the small wheels are not suited to rough ground, it folds and unfolds easily and has decent storage space under the seat.
The size and manoeuvrability of the Maclaren, suitable from birth, make it suitable around town and in more confined areas like in the shops or at the market. Being light meant that manoeuvring around obstacles posed no problems.
The Maclaren has smaller wheels than many other strollers, which limits its ability on rough and uneven ground.
The stroller handles are not adjustable, but are foam covered for extra comfort. Most parents found the handles comfortable.
The Maclaren is very easy to fold and unfold, and the clip that holds the pushchair closed when folded clicks into place itself. There is also a handle for carrying the stroller when folded.
The backrest can recline in four different position, and was easy to raise up. Lowering the seat position is trickier though and needs two hands as each side has to be released independently.
There is good storage under the seat as well as a smaller pocket on the back of the hood. There is also a sun/rain visor, and a rain cover is also included in the price.
Pros: Best Buy, easy to push and steer, lightweight, folding/unfolding, easy to carry folded, storage
Cons: Not suited to bumpy terrain