Ultimately, you'd need to discuss the situation with BT Openreach. Indeed, I'm surprised you didn't do this before you started the petition, as you would then know the reasons why you haven't been included in the roll-out so far, whether there is any hope of you being included in the remaining commercial roll-out, and what level of commitment of signatories to the petition may change Openreach's mind.
If your estate is a third exchange only lines, the other two thirds of lines are split across four PCPs (green cabinet, each of which would need a 'twin' cabinet for FTTC), two of the PCPs would need very expensive work to get a power feed to them, many of the lines are more than 1km from the PCP and there's no existing fibre spine nearby and no ductwork to the existing fibre spine, you have just about every reason for BT not to deploy and the estate is never likely to be included in BT's commercial roll-out, no matter what level of commitment you can get from the residents. All these problems are unlikely to exist on one estate.
If all the lines on your estate originate from a single PCP, the vast majority are less than 500m long, a power feed would be inexpensive and an existing fibre spine runs nearby, BT Openreach may be fairly easily swayed to roll-out FTTC to your estate. Indeed, if it is a new estate, you may be picked up by the in-fill programme - quite often new estates did not feature in original deployment plans but have a clear rationale for roll-out when BT consider adding additional cabinets to already upgraded exchanges.
There's a difference between "I want FTTx on the exchange" and "I commit myself to order FTTx within 6 months of it becoming available". It's easy to make the former statement, but ultimately it means little - it may be motivated by concerns, such as house prices or ease of future sale, other than a desire to order service. The latter commitment makes a sound business case for roll-out, especially if it's signatures from 330 houses, not 330 individuals from a rather lower number of houses.