thechick I went back to work at 5 and 6 months, so most of my kids food was milk. I expressed from a couple of weeks, gradually introduced a bottle late evening of EBM, then built up a supply in the freezer. I just had a cheap avent hand pump and did fine. I did express at work but was not enough to keep up with the amount needed - three bottles I think it was a day. I would feed them first think, quick feed before work, feed on arrival home and in evening. As they were more established on solids, I cut out day bottles, but continued to express the same. Fed as usual on days off.
At 9 months your baby will be pretty well established on solids so not such a big frozen supply would be needed. Likely just feed when at home, and one bottle during the day. I would be tempted to introduce that in the way of formula personally to save hastle of expressing at work. I used to use EBM on cereal etc, but once eating well, use formula or cows milk.
Expressing at work is not fun. Considering I work for the NHS I had to fight for a fridge, and there are no allowances for workload even though you are entitled to time to express. I just had to work extra hard the rest of the time. It is hard swapping from challenging work to baby thoughts to produce milk.